Like larger denominations, the $5s and $10s contain a slew of new antitheft devices - including more intricate hand-engraved portraits of Abraham Lincoln and Alexander Hamilton - to protect against threats posed by high-tech improvements in copy machines, scanners, and printers.

Other security features on the new bills include a polymer security thread that glows when held up to ultraviolet light and microprinted words that defy photocopying. Finely engraved lines that are hard for even high-resolution scanners to "see" have been added.

The Treasury Department, which approves all new designs, didn't opt for any radical artistic changes. But larger, block-like numbers on the backs of the new bills make them easier to read for the visually impaired.

More trees now frame the Treasury building on the back of the new $10. What looked like a tiny Model T Ford on the old $10 is gone. (One rumor: other carmakers complained.)

Claudia Dickens, a spokeswoman for the Bureau of Engraving and Printing, says many people have suggested that the color of US money be changed to blue or red. "Color is pretty. But it's too costly," Ms. Dickens says. It now costs about 5 cents to make a single bill.

Many people have also lobbied to replace the portraits with more modern American heroes, like Franklin Delano Roosevelt and Martin Luther King. Elvis was also a heavy favorite. But Dickens says since US currency is the most used in the world, consistency is a priority. Besides, she says: "If you cater to one person, you have to cater to everyone."

For a look at the artists who design the money, see tomorrow's Home Forum pages.